Tubular apparatus, in particular a steam generator

ABSTRACT

A tubular apparatus, particularly a steam generator, having a casing, a plurality of tubes which are to be installed in the casing, and a series of gratings for separating the tubes a certain distance. The gratings consist of a frame, holders in the frames, and a plurality of grating bars maintained by the holders. One of the numerous advantages attained by the invention lies in that only a specified portion of the grating bars are installed initially so that a passage is formed that allow access by personnel to the fitting of the tubes.

United States atent [191 Tegethoff Sept. 23, 1975 TUBULAR APPARATUS, IN PARTICULAR A 3,399,719 9/1968 Forrest et al. 165/162 x STEAM GENERATOR 3,420,297 1/1969 Romanos 165/162 [75] Inventor: Helmut Tegethofi, Oberhausen, FOREIGN PATENTS OR APPLICATIONS ny 536,138 5/1941 United Kingdom 122/510 [73] Assignee: Gutehoffnungshutte Sterkrade Aktiengeseuschafl, Germany Primary Exammer-Charles J. Myhre Assistant Examiner-Theophi1 W. Streule, Jr. [22] F1led: Dec. 20, 1973 Attorney, Agent, or FirmToren, McGeady and 21 Appl. No.: 426,573 Stanger 7 AB TRA T [30] Foreign Application Priority Data [5 1 S C Dec 21 1972 German 2262621 A tubular apparatus, partlcularly a steam generator, y having a casing, a plurality of tubes which are to be [52] U S Cl 165/162 122/510 installed in the casing, and a series of gratings for sep- [51] E328}? 9/00 arating the tubes a certain distance. The gratings con- [58] 165/16] sist of a frame, holders in the frames, and a plurality of 165/162 grating bars maintained by the holders. One of the numerous advantages attained by the invention lies in that only a specified portion of the grating bars are in- [56] References Cited stalled initially so that a passage is formed that allow UNITED STATES PATENTS access by personnel to the fitting of the tubes. 2,198,529 4/1940 Fields 165/162 x 2,884,911 5/1959 .lankowski 122/510 3 Clams, 4 Drawmg Flgures US Patent Sept. 23,1975 Sheet 1 of3 3,907,031

US Patant Sept. 23,1975 Sheet 2 of3 3,907,031

TUBULAR APPARATUS, IN PARTICULAR A STEAM GENERATOR SUMMARY OF THE INVENTION The present invention concerns a tubular apparatus, in particular a steam generator, in the casing of which straight or U-shaped tubes are installed which are maintained at a certain distance of each other by unevenly spaced gratings, with the grating bars being fastened in a frame encircling the tube bundle.

With previously known tubular apparatuses the grating bars are fixed to the frame by welding. As a consequence the gratings are relatively rigid. If they are not accurately aligned or if the grating bars become distorted e.g., by welding, threading the tubes is difficult or the tubes might even by damaged by fluting.

For reasons of fabrication the tube bundle cannot be installed in various instances before the shell of the tubular apparatus is fixed to the tube sheet so that the tubes must then be blindly inserted through the gratings. With tubular apparatuses having a large shell diameter, help in inserting the bars can be given by the assembly personnel provided manways permittingaccess are arranged in the grating structures.

The task to be accomplished by the present invention was to simplify the threading of tubes in a tubular apparatus of the design specified at the beginning and to improve working conditions during assembly.

In accordance with the present invention this purpose is achieved by providing holders in the grating frames into which the grating bars can be plugged. According to a predominant feature of the present invention the grating structure of the tubular apparatus is so designed as to incorporate recesses in the front faces of the frame into which the holders are inserted, with the holders having a slot in their side which is in alignment with a recess in the frame inner side and with the grating bar engaging with the recess in the frame inner side through the slot provided in the holder.

The grating bars not being welded direct to the frame, the danger of bar distortion is eliminated in tubular apparatuses incorporating the present invention. The recesses in the frame front-side and the frame inner side can be accurately made so that the gratings can be installed to be completely congruent. If the holders used have a circular cross-section the gratings are of a certain elasticity since the holders can rotate by a certain amount in the frame recesses which in this case are bores.

The main advantage of a tubular apparatus incorporating the present invention is that the grating bars can also be plugged into the frames as late as in the tube fitting stage. This permits the adoption of a basically new assembly technique.

Therefore, the present invention further provides for the use of grating structures where only part of the overall grating area is fitted with bars prior to installing the tubes. The bars of the free grating area are plugged in while fitting the tubes and will be located horizontally in this part of the grating. The grating halves initially fitted with bars are offset by 180 from each other within the tubular apparatus, permitting access to the apparatus while the tubes are installed without the need for any additional manways in the grating structures.

The present invention will be exemplified below by reference to the following Figures:

FIG. 1 is a longitudinal section of a tubular apparatus incorporating the features of the present invention.

FIG. 2 shows Detail A.

FIG. 3 represents Section IIIIII to FIG. 2.

FIG. 4 is a plan view of a grating at the beginning of the tube-fitting process.

The tubular apparatus, in this case a steam generator, consists of a casing 1 into which U-shaped tubes 2 are installed. Within the casing l the bundle of tubes 2 is encased in a shell 3 extending down to near the tube sheet 4. Instead of U-tubes, straight tubes can be used as well.

The tubes 2 are fixed in the tube sheet 4 which is welded up with the casing 1. Assembly of the casing 1 with the tube sheet 4 and shell 3 is made prior to fitting the tubes 2.

Within the shell 3 the tubes 2 are maintained at a certain distance of each other by means of gratings 5. An equal distance between the individual gratings 5 is ensured by the provision of spacers 6.

The grating structures 5 comprise an annular frame 7 with intermediate braces 8. On either front face the frame 7 is alternately provided with bores 9 into which a sleeve 10 is inserted. in their side the sleeves 10 have a slot 11 with a cross-section slightly larger than that of the grating bars 12. The slot length is smaller than the length of the sleeve 10.

On the side, at a certain distance from the front face, two continuous grooves 13 are arranged in the frame 7 with a width slightly larger than the width of the grating bars 12. The sleeves 10 are so inserted in the frame 7 that the slot 11 is in alignment with the groove 13. The grating bar 12 is inserted into thegroove 13 of the frame 7 through slot 1 1 in sleeve 10 and so held in position.

The central brace 8 is likewise provided with holders as described above. Before being inserted into the annular frame 7 and the brace 8, the bars 12 are slightly bent. The process of insertion is facilitated by rotating the sleeves 10 in their bores. in addition, the bars 12 can be welded up with the sleeves 10.

The gratings can be installed into the casing l in completely pre-fabricated state, i.e., with mounted bars 12. On the other hand, however, the above method of providing holders for the grating bars in the frame 7 also permits to insert the bars during tube fitting. To this end, only part preferably one half of the grating is fitted with bars 12 initially and then inserted in the casing 1. In this pre-fabricated grating section the bars are arranged in conformity with the specified triangular tube pitch at an angle of 60 or from the middle plane. In the requirement under consideration the grating bars 12 are preferably welded up with the sleeve 10. The bars 12 of the free grating area are only inserted into the casing 1 while installating the Utubes 2. First, a row of tubes is threaded upon which the bar 12 limiting this row is plugged into the respective holders in the frame 7. Following this, the next row of tubes is threaded and another bar 12 inserted. This procedure is repeated until the entire cross-section of the tubular apparatus is fitted with tubes 2. FIG. 4 shows these operations accomplished for the first two rows of tubes. In this section of the gratings the bars 12 are arranged horizontally.

The grating halves fitted with bars are offset by from each other so that the assembly personnel can climb through the respective free halves arranged alternately on the righthand and lefthand sides of the steam generator (see line 14 in FIG. 1) and help to thread the tubes from inside the casing. As tube-fitting progresses, the free sections of the gratings become smaller so that the last few tubes must be threaded blindly".

Instead of sleeves as specified above, round bars or holders of any other cross-section can be used. Similarly, the layout of the grating according to the present invention is not restricted to the triangular tube pitch of the above example.

What we claim is:

l. A spacer for the tubes of a heat exchanger. in particular a steam generator, having a tube bundle comprising a plurality of grating structures, each grating structure comprising a series of grating bars, a ringshaped frame surrounding the tube bundle and having a series of bores formed in at least one face thereof and extending into said frame, and a series of grooves, one

groove of said series corresponding with one of the bores of said series of bores and formed within said frame to intersect with the corresponding bore, and a plurality of sleeves for holding said grating bars. each of said sleeves having a slot therein and rotatably mounted within one of said bores so that the slot is aligned with a respective groove.

2. A spacer according to claim 1, wherein said series of bores are formed in both faces of said frame, each bore extending into said frame a distance greater than the width of a corresponding groove.

3. A spacer according to claim 1, wherein said frame further comprises a central brace for dividing said frame into two sections, the faces of said central brace forming part of said faces of said frame, whereby the rods are mounted in said frame by engaging each end thereof with a sleeve.

l l l 

1. A spacer for the tubes of a heat exchanger, in particular a steam generator, having a tube bundle comprising a plurality of grating structures, each grating structure comprising a series of grating bars, a ring-shaped frame surrounding the tube bundle and having a series of bores formed in at least one face thereof and extending into said frame, and a series of grooves, one groove of said series corresponding with one of the bores of said series of bores and formed within said frame to intersect with the corresponding bore, and a plurality of sleeves for holding said grating bars, each of said sleeves having a slot therein and rotatably mounted within one of said bores so that the slot is aligned with a respective groove.
 2. A spacer according to claim 1, wherein said series of bores are formed in both faces of said frame, each bore extending into said frame a distance greater than the width of a corresponding groove.
 3. A spacer according to claim 1, wherein said frame further comprises a central brace for dividing said frame into two sections, the faces of said central brace forming part of said faces of said frame, whereby the rods are mounted in said frame by engaging each end thereof with a sleeve. 